Experimental Investigation And Theoretical Analysis Of Over-loaded RC Bridge Strengthened With CFS

In recent years, the traffic volume and load carried per automobile are increased very quickly, but the former standards set for design and construction of bridge in china are very simple. This confliction made many old bridges work under "overloaded" condition. Strengthening with CFS is an important method to upgrade those bridges.Until now, overloaded RC bridges is far from fully studied. Research of the bridges which are unloaded while strengthening is even less. For lacking of understanding, most of overloaded bridges which are unloaded while strengthening are strengthened as perfect bridges. In a certain degree, the design of those bridges depends largely on experience of designer. This simplified method is suitable for the bridge which are working under low load before strengthening, and with a plastic state, but it's not suitable for overloaded one. It can cause trouble to those bridges.In this paper, the behavior of overloaded bridges, which have been unloaded before strengthening, and strengthened with epoxy bonded CFS, is carefully studied. The principal research work and innovations are brought forward, including:1. The study fills in a gap in the field of strengthening of overloaded RC bridges with epoxy bonded CFS. On the base of experimental study, the flexural and shear behavior after strengthening are fully recognized, the detail of how the preload, which has been unloaded, affect the result of strengthening is carefully studied. This innovative work afford basis for judging the suitability of CFS strengthening and design theory of CFS strengthening.2. An FEM model, which has considered the effect of preload and nonlinear of material, is set up. The accuracy of the FEM model is tested according to the experimental result. The loading process analysis of structure is realized with the FEM model.3.The FEM model and result of study are used successfully on a real bridge, which has been put into use before strengthening. The preload of the bridge is presumed correctly combining the result of dead load experiment and loading history. The spatial analysis, combining the effect of loading history, nonlinear of material, can not only be used on member analysis, but also on structural analysis. The behavior analysis of the bridge under different level of load is carried out. According to the calculated results, failure characters, the safety of the bridge under design ultimate load are evaluated.